Use Of Powder Coated Nickel Foam As A Resistor To Increase The Temperature of Catalytic Converter Devices With The Use Of Electricity

ABSTRACT

The disclosed invention relates to the optimization of catalytic reactions in diesel engines. A powder-coated nickel or other metallic foam is used as both the substrate and a resistor in a catalytic converter. The disclosed method uses a closed-loop system to heat the metallic foam with electric current to heat the diesel exhaust and thereby optimize the temperature at which the catalytic reaction occurs. The disclosed apparatus comprises a metallic foam substrate with a catalytic coating. The substrate is heated with electrical current to optimize the catalytic reaction. A variety of washcoats and/or catalysts may be used to coat the metallic foam substrate and the optimal temperature will depend on the catalyst used.

This disclosure relates to the optimization of the reaction in acatalytic converter. More particularly, this disclosure relates to theuse of powder-coated nickel foam as a resistor to increase thetemperature of a catalytic converter device and thereby increase theefficiency of the device.

BACKGROUND OF THE INVENTION

The temperature of a catalytic converter is one of the most significantfactors which affects its efficiency. The efficiency drops off rapidlyat both high and low temperatures, leaving a relatively narrow band ofoperating temperatures within which efficiency is highest. Mostimportantly, when automobile and truck engines begin operation, thecatalytic converter is at a temperature too low to produce the reactionsnecessary to reduce the pollutants in the exhaust. When an engine firststarts, the catalytic converter does almost nothing to reduce thepollution in the exhaust.

In the past, many catalytic converters have used the heat present in thevehicle exhaust stream to produce the temperatures necessary for thecatalytic reactions to occur that transform harmful exhaust gasesprimarily carbon monoxide (CO) and nitric oxide (NO) into less harmfulgases, primarily carbon dioxide, nitrogen (N₂) and oxygen (O₂) that arevented into the atmosphere. One solution used to heat the catalyticconverter is moving the catalytic converter closer to the engine,allowing hotter exhaust gases to reach the converter. This positioningallows the catalytic converter to heat up faster, but may reduce thelife of the converter by exposing it to extremely high temperatures.

Preheating the catalytic converter is another way to increase efficiencyand reduce emissions. One of the most prevalent ways to preheat theconverter is to use electric resistance heaters. The 12-volt electricalsystems on most cars and trucks cannot provide enough energy or power toheat the catalytic converter fast enough. Hybrid cars with high-voltagebattery packs can sometimes provide enough power to heat up thecatalytic converter very quickly.

Catalytic converters in diesel engines are even less efficient thanstandard engines because diesel engines run cooler than standardengines. One solution to this problem is a system that injects a ureasolution (an organic compound made of carbon, nitrogen, oxygen andhydrogen) in the exhaust pipe before it reaches the converter. The ureaevaporates and mixes with the exhaust, creating a chemical reaction thatreduces nitrogen oxides (NO_(x)). The urea reacts with NO_(x) to producenitrogen and water vapor, reducing the nitrogen oxides in exhaust gases.Another method is heating a diesel particulate trap sufficiently toincinerate the soot formed in the trap as a result of the condensationof soluble organic fractions in the exhaust stream. This heating isaccomplished thermally with exhaust gas.

BRIEF SUMMARY OF THE INVENTION

This invention uses metallic foam as both a support for the catalyst(s)and as the resistor itself when attached to a closed-loopthermostatically-adjusted controller. This invention uses the residualelectrical energy generated by the engine, much as in the manner ofother electronic devices, such as the vehicle radio, to heat thecatalytic converter directly to a more efficient temperature at which toconduct the catalytic reaction. The disclosed invention consists of amethod of optimizing the temperature of diesel engine exhaustcomprising: providing a substrate consisting of a metal foam; coatingthe substrate with a catalytic material; heating the substrate withelectric current to a temperature range designed to optimize thecatalytic reaction; and causing the diesel engine exhaust to flow overthe substrate so that the catalytic material interacts with saidexhaust. In all embodiments of the invention, the substrate may be inthe form of nickel foam or metal foam. The catalytic material may alsocomprise a washcoat. The catalytic material may be comprised of variouscatalysts, including: an iron manganese catalyst; a titanium dioxidecatalyst; a selective catalytic reduction (“SCR”) catalyst; or aplatinum catalyst.

The disclosed invention also may consist of a diesel engine exhaustsystem comprising: a housing having an inlet for receiving dieselexhaust; a metallic foam substrate within the housing, the substratehaving a catalytic coating; an electrical system for heating saidsubstrate; and an outlet for emitting diesel exhaust. In all embodimentsof the system, the substrate may be in the form of nickel foam or othermetal foam. The catalytic coating may also comprise a washcoat. Thecatalytic coating may be comprised of various catalysts, including: aniron manganese catalyst; a titanium dioxide catalyst; an SCR catalyst;or a platinum catalyst.

BRIEF DESCRIPTION OF THE DRAWINGS

A schematic for the claimed metallic foam substrate and resistor isshown in FIG. 1, which shows the source of the current 1, a DCcontroller 2, the metal foam sheet 3, the buss bars 4 and thermocoupleor other pyrometric device 5. A schematic for the catalytic converterdevice is shown in FIG. 2, which shows the flow of the exhaust 1, theelectrified catalyst 2, including the foam substrate 3, the control unit4, the diesel particulate filter 5, the second catalyst 6 and thehousing 6.

DETAILED DESCRIPTION OF THE INVENTION

The disclosed invention describes the use of a power-coated nickel foamas a resistor to increase the temperature of the catalytic converterdevice and thereby increase the efficiency of the device. Traditionally,a catalytic converter consists of several components: (1) the substrate,which is most often a ceramic honeycomb or stainless steel foilhoneycomb; (2) the washcoat, which is often a mixture of silicon,aluminum and other elements and which forms a rough, irregular surfacewhich has a far greater surface area than the substrate surface; and (3)the catalyst itself, which is often a precious metal such as platinum orpalladium. The catalyst is added to the washcoat (in suspension) beforeapplication to the substrate.

In the disclosed method and apparatus, the substrate is a powder-coatednickel foam, which is manufactured in accordance with the processdisclosed in German Patent DE1025006009164A1, dated Feb. 20, 2006,entitled “Diesel Particle Filter with open-pored metal foam” held byInco Limited. The good ductility and high flexibility of the 100%open-pore material allows the substrate design to be determined freely.Different porosities make it possible to define the level of deep-bedfiltration in the system. The foam acts as an effective substrate due toits high temperature and corrosion resistance, coupled with a very goodsoot storage capacity. During the manufacturing process, the nickelmetal foam is coated and thermally treated with a high-alloy metalpowder tailored to the particular application and design. Fusion occurs,enlarging the specific surface of the light metal foam. At the sametime, the temperature resistance of the thermal conductive alloy foamincreases up to 1,000° C. with peaks of up to 1,200° C. The foam isflexible, ductile, and can be cut at any length. The material may besintered and manufactured as sheets. Other types of metallic resistanceproducts are known in the art and may also be used in the disclosedmethod and apparatus.

A number of different wash coats and/or catalysts can be applied to thefoam so that the foam can be used as a catalytic converter. Thecatalysts applied can increase the amount of nitrogen dioxide (NO₂),decrease the amount of nitrogen oxides (NO_(X)), reduce the presence ofcarbon monoxide (CO), and reduce the presence of hydrocarbons. Further,the foam can act as a DPF, which passively regenerates itself. Asdisclosed in German Patent DE102006009164A1, the powder coating appliedto the nickel foam is a combination of iron and chromium. After thepowders are applied, the material is sintered to form a material with amuch larger surface area.

The powder-coated nickel foam has no catalytic properties itself but isan excellent support for catalytic material, including an appropriatewash coat and/or catalyst. At least four different catalytic coatingshave been applied to the foam, including: (1) an iron manganese catalystthat converts CO to carbon dioxide (CO₂); (2) a catalytic washcoat andplatinum catalyst which convert CO to CO₂, and hydrocarbons to CO₂ andwater vapor; (3) a catalyst made from titanium dioxide (TO₂), whichconverts NO₂ to nitric oxide (NO); and (4) a catalyst that convertsNO_(x) to nitrogen gas (N₂) and water. The catalyst that converts NO_(x)to nitrogen gas (N₂) and water may be any type of SCR catalyst,including oxides of base metals (such as vanadium and tungsten) andzeolites. Other catalytic coatings may exist commercially or in thecurrent art that can be applied to the nickel foam.

It is well-known that each catalytic material has a temperature wherethe catalyst is most effective. In many diesel systems, the exhaustemissions never or only slowly reach the temperature where the catalystis most effective. In the disclosed invention, the metal foam, which isbeing used as the catalytic support, is imbued with electric current tocontrol the catalyst at the most efficient temperature with a smallamount of current. The current is generated as a by-product of engineactivity, so it is unnecessary to introduce additional energy into theengine system. The system is a closed-loop system that uses athermocouple to measure the temperature of the exhaust stream and thenregulates the amount of current to maintain a preselected temperature.The circuitry for the system can be designed without undueexperimentation by those skilled in the electronic arts.

The disclosed apparatus consists of an adjustable direct-currentelectricity source with the circuit attached either to a battery orgenerator source that can supply adequate current to increase thetemperature of the metal foam. The current source isthermostatically-controlled by a proportionate controller that receivestemperature input from a thermocouple or other type of temperaturesensor, including but not limited to, resistance thermometers,filled-system thermometers, bimetal thermometers or radiationpyrometers. The system also includes a controller which can beconstructed in accordance with devices described in Chapter XXII of theChemical Engineer's Handbook. The current is conveyed by wires connectedto buss bars connected to the opposite sides of a sheet or other form ofthe metallic foam. The foam is mounted in a container that receives theemissions from the engine, as is used typically to house the catalyticconverter supports. In the disclosed invention, however, the catalyticconverter support also acts as a heater to heat the catalyst andsurrounding exhaust to optimal temperatures.

1. A method of optimizing the temperature of diesel engine exhaustcomprising: providing a substrate consisting of a metal foam coated witha catalytic material; heating the substrate to a temperature rangedesigned to optimize the catalytic reaction by passing an electriccurrent through the substrate; and causing the diesel engine exhaust toflow over the substrate so that the catalytic material interacts withsaid exhaust.
 2. A method according to claim 1 wherein said substrate isin the form of nickel foam.
 3. A method according to claim 1 wherein awash coat is combined with a catalyst to form the catalytic material. 4.A method according to claim 1 wherein said catalytic material comprisesan iron manganese catalyst.
 5. A method according to claim 1 whereinsaid catalytic material comprises a catalyst consisting of titaniumdioxide.
 6. A method according to claim 1 wherein said catalyticmaterial comprises an SCR catalyst.
 7. A method according to claim 2wherein a wash coat is combined with a catalyst to form the catalyticmaterial.
 8. A method according to claim 2 wherein said catalyticmaterial comprises an iron manganese catalyst.
 9. A method according toclaim 2 wherein said catalytic material comprises a catalyst consistingof titanium dioxide.
 10. A method according to claim 2 wherein saidcatalytic material comprises a catalyst consisting of an SCR catalyst.11. A method according to claim 3 wherein said catalytic materialcomprises an iron manganese catalyst.
 12. A method according to claim 3wherein said catalytic material comprises a catalyst consisting oftitanium dioxide.
 13. A method according to claim 3 wherein saidcatalytic material comprises a catalyst consisting of a an SCR catalyst.14. A method according to claim 3 wherein said catalytic materialcomprises a catalyst consisting of platinum.
 15. A method according toclaim 7 wherein said catalytic material comprises an iron manganesecatalyst.
 16. A method according to claim 7 wherein said catalyticmaterial comprises a catalyst consisting of titanium dioxide.
 17. Amethod according to claim 7 wherein said catalytic material comprises acatalyst consisting of an SCR catalyst.
 18. A method according to claim7 wherein said catalytic material comprises a catalyst consisting ofplatinum.
 19. A diesel engine exhaust system comprising; a housinghaving an inlet for receiving diesel exhaust; a metallic foam substratewithin the housing, the substrate having a catalytic coating; anelectrical system for heating said substrate; and an outlet for emittingdiesel exhaust.
 20. A system according to claim 19 wherein saidsubstrate is in the form of nickel foam.
 21. A system according to claim19 wherein said catalytic coating also comprises a washcoat.
 22. Asystem according to claim 19 wherein said catalytic coating comprises aniron manganese catalyst.
 23. A system according to claim 19 wherein saidcatalytic coating comprises a catalyst consisting of titanium dioxide.24. A system according to claim 19 wherein said catalytic coatingcomprises a catalyst consisting of an SCR catalyst.
 25. A systemaccording to claim 20 wherein said catalytic coating also comprises awashcoat.
 26. A system according to claim 20 wherein said catalyticcoating comprises an iron manganese catalyst.
 27. A system according toclaim 20 wherein said catalytic coating comprises a catalyst consistingof titanium dioxide.
 28. A method according to claim 20 wherein saidcatalytic coating comprises a catalyst consisting of a an SCR catalyst.29. A system according to claim 21 wherein said catalytic coatingcomprises an iron manganese catalyst.
 30. A system according to claim 21wherein said catalytic coating comprises a catalyst consisting oftitanium dioxide.
 31. A system according to claim 21 wherein saidcatalytic coating comprises a catalyst consisting of a an SCR catalyst.32. A system according to claim 21 wherein said catalytic materialcomprises a catalyst consisting of platinum.
 33. A system according toclaim 25 wherein said catalytic material comprises an iron manganesecatalyst.
 34. A system according to claim 25 wherein said catalyticmaterial comprises a catalyst consisting of titanium dioxide.
 35. Asystem according to claim 25 wherein said catalytic material comprises acatalyst consisting of a an SCR catalyst.
 36. A system according toclaim 25 wherein said catalytic material comprises a catalyst consistingof platinum.